August 1997
WASHINGTON, D.C.— Environmental control can be an inexpensive and extremely effective management technique for allergic disease with few adverse events, according to Laurie J. Smith, MD, assistant chief of the Allergy Clinical Immunology Department at Walter Reed Army Medical Center here.
However, "I do not agree with whole-hearted recommendations of environmental-control measures to all parents who have children that wheeze or have stuffy noses and may have allergies," said Smith.
The exception to this rule is highly allergic families, where environmental control may prevent the child from developing allergies, she said. "But for your average kid who comes in with a stuffy nose, I am not going to recommend to the mother that she should clean up the house and do all these other things. I don't think that it's fair unless clinical sensitivity to dust mite and/or animal dander has been proven or is highly likely."
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| Common problems that cause indoor air pollution: dust mites, cats and second-hand smoke. Photo courtesy of Thomas Rosenthal |
Dust mite allergy is the most common allergen in the world, noted Smith, who spoke in San Diego at the American Academy of Pediatrics' Spring Meeting. "It simply lives and dies and defecates, particularly in the nice, warm moist environment of your bed or carpeting." In fact, the feces is more allergenic than the actual microscopic organism. Nonetheless, "There is no doubt that if you can decrease the exposure to mites in the environment, you may be able to decrease the symptomatic allergic diseases of asthma and rhinitis."
For documented or potential mite-sensitive patients, Smith recommends concentrating on temperature and humidity. "You should keep the indoor temperature around 70° F year-round, plus keep the humidity down." Running the air-conditioner instead of opening doors and windows in the summer will help maintain humidity of less than 50%. In the winter, "if your environment is very dry, and you have to add humidity, counsel your families to invest in a humidity-gauge," she said. An extremely humid basement can also be equipped with a dehumidifier.
Smith advises removing dust catchers from the child's bedroom, such as stuffed animals, curtains, canopies and upholstered furniture. "It's an area you can modify without affecting the whole family that much. It's a practical place to make a difference."
In addition, cover the mattress, box springs and pillow with impermeable covers. "These are not the plain rubber sheets for a bed wetter. These go all around the mattress and zip, and all around the pillow and zip. It is not just a plastic cover."
Impermeable covers now come with fabric on one side and plastic on the other, noted Smith, "so you have something that's not too unpleasant to sleep on, yet does the job."
Washing all the bedding every two weeks in hot water (130°F) is important. Ideally, the carpeting should also be removed, but this is an expensive proposition that is often resisted. The truth though "is that you are never going to eliminate mites when the carpet is still there," said Smith.
Three percent tannic acid and benzyl benzoate powder are two chemical treatments to decrease mite allergen in carpets and upholstered furniture. "These probably need to be used more frequently than the instructions recommend," said Smith, who has chiefly abandoned this treatment in favor of impermeable covers and washing.
Frequent vacuuming, central-air filtering systems, room air cleaners and cleaning out the ducts of the heating system are other measures that probably are not effective, said Smith.
There are no hypoallergenic cats or dogs. However, cats are much more allergenic than dogs. "The allergen with cat is simply more powerful and more likely to evoke an allergic response. This response is also more likely to be severe," explained Smith. "I have more tears in my office over cats than over anything else. Cats are a very emotional issue."
The primary cat allergens come from sebaceous gland cells and salivary glands. Particles remain suspended in undisturbed air for long periods. "It is very light and very sticky," she said, sticking to curtains, walls and pictures. "So, if you push the cat out the door tomorrow, you have a heavy burden of cat allergen that will persist for a long time."
The best treatment for cat allergy is the removal of the cat, accompanied by a thorough household cleaning. "Yet even with vigorous cleaning, it may take 20-24 weeks for cat antigen levels to fall significantly," noted Smith. Studies also indicate that allergens can persist full force in mattresses for more than five years after removing the cat.
A compromise management entails keeping the cat out of the child's bedroom, covering the mattress and pillows, investing in a room air cleaner (with HEPA filter) and keeping the cat out of play areas (family room) as much as possible. Some studies advocate cat washing as an effective compromise. However, "recent data suggests that even washing doesn't make that much difference," said Smith.
Indoor air pollution is another risk factor. Tobacco smoke is the No. 1 irritant. "I tell my families that if they must smoke, it can never be inside the house. It must be outside, whether it's snowing or hailing or 100° F — and never in the car. This is all non-negotiable," said Smith.
Another red flag is nitrogen dioxide, which can be a problem with unvented gas ranges, pilot lights, some gas furnaces, kerosene heaters and wood burning heat sources. "This can be a fairly significant irritant in children," said Smith.
Control of indoor air pollution consists of venting furnaces to the outdoors, annual inspection and cleaning of the central heating unit, keeping gas appliances adjusted, tight ventilation of wood stoves, adequate fresh air intake and having the garage isolated from the home because of problems with carbon monoxide.
Smith encourages practitioners to read Taming Asthma and Allergy by Controlling Your Environment: A Guide for Patients by Robert A. Wood, MD. The guide is available from the Asthma and Allergy Foundation of America, MD Chapter, 5601 Loch Raven Blvd., Baltimore, MD 21239-2995, (410) 532-4135.
For more information:
- Smith LJ. Environmental control in allergic diseases: resources in managing allergic diseases. Presented at the American Academy of Pediatrics. May 10-13. San Diego.
- Platts-Mills TAE. Controlling indoor allergens in patients with asthma. J Respir Dis. 1992;13:S20-7.
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